One method of producing microstructures is projection exposure, for example, in which a mask is demagnified by a lens system and typically imaged on the scale of 5:1 or 4:1, wherein structures of one micrometer or less can be produced by single exposure. Since imaging a mask in that method typically cannot cover an entire wafer, the wafer is moved and positioned such that the images of the mask lie on a grid with narrow tolerances (so-called “step-and-repeat” method). The apparatuses used for this purpose are called “wafer steppers”. However, such apparatuses are expensive and not part of standard equipment in the production of radiation-emitting semiconductor components. By way of example, projection exposure apparatuses functioning according to the scanner principle are used in the production of radiation-emitting semiconductor components. In contrast to steppers with the step-and-repeat principle, the mask is illuminated only in a narrow strip and passed through this light strip in a manner similar to that which occurs in line scanners or photocopiers. In that case, the mask is imaged in particular on a scale of 1:1. Hitherto, structure sizes of 2.5 μm with distances of 5 μm have been able to be obtained by single exposure in such exposure apparatuses.
There is, however, a need to provide a lithographic method having improved resolution of producing structures in radiation-emitting semiconductor components.